The nicotinic Acetylcholine Receptor (nAChR) is the major class of neurotransmitter receptors that is involved in many neurodegenerative conditions such as schizophrenia, Alzheimer?s and Parkinson?s diseases. The N-terminal region or Ligand Binding Domain (LBD) of nAChR is located at pre- and post-synaptic nervous system, which mediates synaptic transmission. nAChR acts as the drug target for agonist and competitive antagonist molecules that modulate signal transmission at the nerve terminals. Based on Acetylcholine Binding Protein (AChBP) from Lymnea stagnalis as the structural template, the homology modeling approach was carried out to build three dimensional model of the N-terminal region of human α₇nAChR. This theoretical model is an assembly of five α₇ subunits with 5 fold axis symmetry, constituting a channel, with the binding pocket present at the interface region of the subunits. α-neurotoxin is a potent nAChR competitive antagonist that readily blocks the channel resulting in paralysis. The molecular interaction of α-Bungarotoxin, a long chain α-neurotoxin from (Bungarus multicinctus) and human α₇nAChR was studied. Agonists such as acetylcholine, nicotine, which are used in a diverse array of biological activities, such as enhancements of cognitive performances, were also docked with the theoretical model of human α₇nAChR. These docked complexes were analyzed further for identifying the crucial residues involved in interaction. These results provide the details of interaction of agonists and competitive antagonists with three dimensional model of the N-terminal region of human α₇nAChR and thereby point to the design of novel lead compounds.

Key words: α₇nAChR; Ligand binding domain; Homology modeling; Acetylcholine; Nicotine; α-bungarotoxin; Protein-protein interaction; Protein-ligand interaction; Evolutionary Trace Analysis; Neurodegenerative diseases.